The present invention relates to a structure of a body skeleton element forming a closed cross-sectional space by an outer panel and an inner panel such as various pillars, a roof side rail, a side sill and the like of a vehicle such as an automobile car, and a method of manufacturing the body skeleton element.
FIGS. 1 through 4 illustrate a structure consisting of an assembly of front pillars, side sills, roof side rails and the like which are conventional body skeleton elements. A front pillar 1 has a closed cross-sectional space which is formed by an outer panel 2 and an inner panel 3. The front pillar 1 has a lower end which is connected to a side sill 4, while an upper end of the front pillar 1 is connected to a roof side rail 5. The roof side rail 5 has a closed cross-sectional space which is formed by a rail outer 6 and a rail inner 7. A front roof rail 9 is connected to an upper side of the front pillar 1 through a three-forked roof rail brace 8. The front pillar 1 is arranged such that a urethane block 10 is filled in a waist section of the front pillar 1, and a foam rubber 11 is filled in an upper end of the front pillar 1. Thus, a sound transmitted from an engine room E is prevented from being transmitted to the interior of a compartment from the pillar closed cross-sectional space through the closed cross-sectional space of the roof side rail 5. In this connection, in FIG. 1, the reference numeral 12 denotes a roof panel; 13, a cowl box; and 14, a front fender. A structure similar to that described above is disclosed in Japanese Patent Laid-Open No. SHO 61-129369, for example.
However, the urethane block 10 is inserted into the pillar closed cross-sectional space from a door-hinge mounting bore 15 which is formed in the inner panel 3 of the front pillar 1. The urethane block 10 does not completely fill in the pillar closed cross-sectional space to every nook and corner. Instead gaps are inevitably defined at the corners of the pillar closed cross-sectional space as illustrated in FIG. 3.
In order to fill the foam rubber 11 as a foaming material, thermally foaming rubber sheets 11a are adhered or glued, respectively to inner side surfaces of the inner panel 3 and the outer panel 2 of the front pillar 1 as indicated by broken lines in FIG. 4, at the upper end of the front pillar 1. After connection of the skeleton elements such as the front pillar 1, the roof side rail 5 and the like, inner and outer surfaces of the skeleton elements are processed in rust preventive, and the outer side surface is finally painted, so that the rubber sheet. 11a is foamed by heating while passing through a paint booth during a drying step.
Since, however, the thermally forming rubber sheet 11a per se is not foamed large in the first place, foaming tends to become insufficient with respect to the dimension or size of the pillar closed cross-sectional space. As a result, gaps occur at the corners of the pillar closed cross-sectional space, and voids occur at the central section of the foam rubber 11. Further, the gaps and the voids are formed under a condition in which they cannot be confirmed from the outside. As a result, there is a defect in that no sound isolating effects can be obtained in spite of the fact that expensive sound isolating measures are performed.
Further, since the thermally foaming rubber sheets 11a are adhered also to the inner side surface of the outer panel 2 of the front pillar 1 as described above, the adhered-to sections are not subjected to the rust preventives. For this reason, there is a chance that rust may gather on the surfaces of the adhered-to sections of the outer panel 2, which are exposed to the outside of the vehicle.